Multistage unloader



G. M. RICHARDS. MULTISTAGE UNLOADER. APPLICATION FILED JULY 3,1918.

1,422,376. Pa nt d uly 11, 1922,

5 f if F MULTISTAGE UNLOADER.

Application filed July 3,

T all whom it may concern.

Be it known that I, GEORGE M. R Iorinnns, a citizen of the United States, resid ng at 7 813 Norwood St, Chestnut Hill, Philadelphia, in the county of Philadelphia and State of Pennsylvania, have 1nvented a certain new and useful Multistage Unloader, of which the following is a specification.

The purpose of my invention is to prov de for unloading an air compressor system with a minimum of loss of energy and without freeing air which has been compressed.

A further purpose is to avoid waste of air used to operate the unloader.

A further purpose is to form the proper time relation, unloading the low pressure compressor cylinder, emptying the inter, cooler and unloading the high pressure cylinder in proper sequence.

A further purpose is to provide a new type of trigger valve for a pressure unloader.

Further purposes will appear in the specification and in the claims.

tion by but two forms, showing combinations which are practical, eflicient and thoroughly reliable and which at the same time well illustrate the principles of my invention. 7

Figures 1 and 2 are end elevations of portions of multi-stage air compression systems showing two similar forms, identical in so far as relates to my invention.

Figure 3 is a vertical central section through a trigger valve embodying my 1nventlon.

In the drawings similar numerals indicate like parts.

Efficient unloading of a multi-stage air compression system requires that the low pressure cylinder be unloaded first, the intercooler emptied next and the high pressure cylinder unloaded last and with a minimum waste of air andenergy. My invention supplies a valve devic for operation upon a pressure unloader between the high pressure cylinder and the receiver which is actuated when the intercooler pressure becomes v sufiiciently low, and is therefore dependent upon the prior actuation of either a suction unloader or a pressure unloader connected with the low pressure cylinder. Because of the fact that this valve device sets off the unloading operation,determining the time Specification of Letters Patent.

I have preferred to illustrate my inven- Patented July ii, was. 1918. Serial No. 243,140.

and performing the unloading function, it has come to be a trigger in the language of the trade and will be referred to herein as a trigger valve.

The compressors with which my invention s intended to be used are motor driven, and it is quite desirable to relieve the motor automatically until a predetermined speed has been reached; also to cut out the load or put it 1n again at predetermined pressures.

In Figure 1 I have shown low pressure cylinder 5, high pressure cylinder 6, intercooler 7, connecting pipes 8 and 9 and an intake 10 for the low pressure cylinder. In this intake I show a suction unloader 11, of which a number of forms are well known in the art, in connection with a trigger valve 12 controlled by the pressure from the air receiver (not shown) through a pipe 13. The valve 14; permits hand control of the flow through this pipe.

The form of trigger valve 12 illustrated for the suction unloader is a form invented by me and now upon the market but is so well known to the trade as to require no further explanation than that which has been given and the fact that this is distributed by YarnalLWaring Company of Philadelphia, in connection with suction unloaders to which it is suited. Its specific character forms no part of my present invention, to which any form of suction unloader and trigger valve therefor are suited. The construction of this trigger valve '12 will be clear by reference to my Patent No. 1,286,781, issued December 3, 1918, entitled Fluid-actuated controlling device.

Between the high pressure cylinder 6 and the discharge pipe 15 therefrom to the receiver, I place a pressure unloader 16 which discharges through pipe 16. There are various recognized forms on the market, manufactured by YarnallWVaring Company among others, all of which require a trigger valve to operate them. Any of these 100 will answer, as the present invention does not involve the detailed character of the pressure unloader.

A trigger valve suitable for operation of the pressure unloader at this point for carry- 105 ing out my invention is shown at 17 and is connected with the air receiver by a pipe 18 and with the intercooler by a pipe 19 controlled by handvalve 20. For convenience the pipe 18 is shown as connected with the 110 ent invention.

against thelower edge 29 recess within the receiver as that results in a loss of energy there as compared witha system such as is shown in Figure 2. ln'elther event'the same character of pres sure unloader is used for the high pressure cylinder with the trigger valve connected in th'e same way, "as the character of low pressure unloading used does not affect the pres- *ot the diaphragm '(in theposition shown) -lS opento the atmosphere through aperture 26. The diaphragm can be moved by hand in a downward direction by lifting theouter "end o't a lever 27 which surrounds it at the innerend and is cushioned from the diaphragm by awasher 28. The lever fulcrums o'f-the cap opening through which it extends.

Upon "one side of the diaphragm (the upper shown) lies a skeleton pin 30 which carries oppositely facing valves 31 and These cooperate with valve seats 33 and 34: about openings 35 and 36. With the diaphragm in the position shown. the valve 31 closes against the seat 33 while. with movemerit of the diaphragm in a downward direction, this valve is opened and the valve '32 closes against seat 3- In order toprovide for manufacture and "assembly ottheparts the upper part otthe cap, carrying seat 33 and passage is made separate from the lower part and threaded into it. I This upper part contains a wool yarn filter 37.

The preferably convex head 38 ot a bolt 39 is pressed againstthe under side of the diaphragm by a helical spring etO which at one end surrounds the stem of the pin and at the other surrounds the stem of a terminal all. Adjustment of the spring is effected by means of a screw 42- w hosc end rests in a terminal. The screw passes througha plug 4L3, by which the lower end of thctrigger valve body is closed. and is locked in adjusted position by nuts lsl. L5.

The space i6 between the valve seats 32 and 33 is connected with the pressure un-' loader 16 by a pipe 47 and the space 48 below the diaphragm is connected with the pipe'19 as 'at 49.

The compression of spring 40 is intended tobe very light so that it will not do much which may be desired.

to supply the intereooler.

more than support the parts and so that any desired extent of overbalance of atmospheric pressure :above the diaphragm as compared with a partial vacuum in the inter-cooler will cause the'diaphragm to depress.

The screw 41 provides quite a delicate adjustment of the parts so as to operate the diaphragm under any degree of vacuum This is set initially or may be changed during operation to suit the needs of different service conditions or the purpose or whim of the user.

In the initial condition of the trigger valve shown in Figure 3 the spring more than counterbal'ances the weight of i the parts,

closing the valve 31 against its seat '33 and opening thepressure unloader 16 to atmospheric pressure through valve-31 When the system shown in Figure 1 is started there is no pressure in any part of it. There being no pressure on. the trigger valve of the suction unloader thepipe 10 is .tully open tothe atmosphere and the low pressure cylinder immediately begins to accumulate pressure 1n the intercoolcr from which the 'hlgh pressure cylinder draws to fill the re ceive'r. This condition obtains and no change takes place in the trigger valve of either unloader until the pressure in i the receiver "reaches its predetermined upper limit, when the pressure upontrigger valve '12 is effective to. operate the suction unloader and close the pipe 10. The supply of air for the low pressure cylinder-being cut oil, it ceases Meantime the high pressure cylinder quickly reduces the pressure in this intercooler until finally a vacuum condition there is attained.

When the intercooler reaches the predetermined degree of vacuum, the air pressure upon the upper face of the diaphragm. added to the weight of the parts, overcomes the support of the spring38 and the valve 'll opens at the same time that'valve closes. This allows pressure from the receiver to pass through the opening 35 and pipe 4-7 to the pressure unlomler 16 operating it and relieving the high pressure cylinder The. operation of the system shown in Figure 2 is the same except that the discharge from the low pressure cylinder is released instead of throttlingits intake.

It will be noted that the low pressure cyli'nder, intcrcoole and high pressure cylinder are lowered in pressure in turn, with a time element between their several operations;

and this time element may be made praclar functions.

It will be noted' that the connections from the receiver to the two unloaders are entirely independent, functionally, and can be used by wholly distinct and separate pipes, as in Figure 2, the use ofthe section of pipe in common in Figure'l being a mere convenience. The twoconnections with the receiver are thus in parallel or multiple, as distinguished from a series connection of one through the other.

The diaphragm is considered herein broadly asa pressure-operated member.

I prefer to operate the trigger valve at intercooler pressures close to the atmospheric pressure and which may range advantageously from a slight pressure above the atmosphere to any desired pressure below. As I can get. the range desired by placing the spring below the pressure-operated memher and would not require downward. pressure by the spring upon the member unless I desired to operate the trigger valve at intercooler pressures higher above the atmosphere than I consider desirable for the most economical operation of the system, I have not deemed it necessary to illustrate any other position oi the spring than the u wardly pressing position. shown though I have worded my claims so as to protect against unauthorized use with the spring in either position.

Having thus described my inventiomwhat I claim as new and desire to secure by Let ters Patent, is:

1. In a multi-stage unloader system, high and low pressure cylinders and an intercooler between them, in combination with a separate unloader and associated. trigger valve for each cylinder, one unloader being a pressure unloader in the discharge pipe and which is initially unloaded, and common pressure supply for each trigger valve.

2. In a multi-stage unloader system, high and low pressure cylinders, and anintercooler between them, in combination with an unloader for each cylinder, a trigger valve for each unloader, a receiver ted by the high pressure cylinder, a connection from the receiver to each trigger valve and a connection from the intercooler to the 4' J2 tiigger .LOI' the high pressuie cylindei un between them and a receiver ted by the high pressure cylinder, in combination with an unloader for the high pressure cylinder and a trigger valve for the unloader connected with the intercooler containing a pressure member open to the atmosphere on one side and to the intercooler pressure on the other side and adapted to operate when the intercooler pressure falls to a predetermined point.

6. In a multi-stage unloader system, high and low pressure cylinders, an intercooler between them and a receiver ted by the high pressure cylinder, in combination with an unloader for each cylinder, the high pressure unloader discharging to the atmosphere, a trigger valve for the low pressure unloader, connected with the receiver to operate by reason of excessive receiver pressure, a trigger valve for the high pressure cylinder, connections between the high pressure unloader, trigger valve and the intercooler to operate with decreasing intercooler pres sure at a predetermined point and connec tions between the trigger valve and the receiver to utilize the receiver pressure for operation of the high pressure unloader when the trigger valve has operated.

7. In a multi-stage system unloader, high and low pressure cylinders and an intercooler between them, in combination with an unloader and trigger valve for the low pressure cylinder, an unloader for the high pressure cylinder, a receiver connected with the high pressure cylinder, a trigger valve tor the high pressure cylinder unloader, connections from the receiver to the trigger valve to operate the unloader with operation of the trigger valve, a diaphragm in the trigger valve, a valve controlled by the diaphragm to close discharge from the unloader and admit receiver pressure therein'when the diaphragm. moves, the one surface of the diaphragm being open to atmospheric pressure, a spring pressing against the diaphragm and fluid connections between the diaphragm and the intercooler to cause the atmospheric pressure to move the diaphragm when the intercooler falls to a predetermined point.

8. A pressure unloader in combination with a trigger valve therefor having fluid connection for receiver pressure, a valve normally closing said. connection and opening the unloader to the atmosphere, a diaphragm normally maintaining the valve in said po sition and open on one side to atmospheric pressure and fluid connection from the opposite side of the diaphragm adapted. to

press against the diaphragm and to be fig overcome by the atmospheric pressure when the pressure on this opposite side of the diaphragm is reduced.

9. In an unloader trigger valve, a trigger. valve body having openings for connection with the receiver pressure, with the unloader, with the atmosphere and with a course of variant pressure adapted to approach or fallbelow atmospheric pressure, valves on opposite sides of the unloader connection adapted normally to close the pressure connection and open the unloader connectionto the atmosphere and in unloading position to open the pressure to the unloader and close the atmospheric connection to the unloader and a pressure member controlling the operation of said valve, open to the atmosphere on one side and to the variant pressure connection on the opposite side thereof. r

10. In an unloader trigger valve, a trigger valve body having openings for connection with the receiver pressure, with the unloader, with the atmosphere and with a source of variant pressure adapted to approach or fall below atmospheric pressure, valves on opposite sides of the unloader connection, adapted normally-to close the pressure connection and open the unloader connection to the atmosphere and in unloading position to connect the pressure with the unloader and close the atmospheric pressure connection, a pressure-operated member controlling the operatlon of said valves open to the atmosphere on one side of the member and to the ,variant pressure connection on the opposite side thereof and spring support for the member to maintain the parts in normal position until the variant pressure reaches a predetermined value.

11. In an unloader trigger valve, a trigger valve body having openings for connection with the receiver pressure, with the unloader, with the atmosphere and with a source of variant pressure, adapted to approach or fall below atmospheric pressure, valves on opposite sides of the unloader connection, adapt: ed normally to close the pressure connection and open the unloader connection to the atmosphere and in unloading position to connect the pressure with the unloader and close the atmospheric pressure connection, a pressure-operated member controlling the operation of said valves open to the atmosphere on one side of the member and to the variant pressure connection on the opposite side thereof and spring support for the member to maintai'nthe parts in normalposition and balance part of the atmospheric pressure.

12. In an unloader trigger valve, a trigger valve body having openings for connection with the receiver pressure, with the unloader, with the atmosphere and with a source of variant pressure adapted to approach or fall below atmospheric pressure,

valves on opposite sides of the unloader connection, adapted normally to close the pressure connection and open the unloader connection to the atmosphere and in unloading position to connect the pressure with the unloader and close the atmospheric pressure connection, a pressure-operated member controlling the operation of said valves open to the atmosphere on one side of the member and to the variant pressure connection on the opposite side thereof, spring support for the member to maintain the parts in normal position and means for adjusting the spring.

13. In an unloader trigger valve, a trigger valve body having openings for connection with the receiver pressure, with the unloader, with the atmosphere and with a source of variant pressure adapted to approach atmospheric pressure, valves on opposite sides of the unloader connection adapted normally toclose the pressure connection and open the unloader connection to the atmosphere and in unloading position to connect the pressure with the unloader and close the atmospheric pressure connection therewith, a pressure operated member controlling the operation of said valve, open to the atmosphere on one side of the member and to the variant pressure connection on the opposite side thereof and a spring pressing against one side of the member and determining the pressure in the variant pressure connection at which the member shall operate. I

14. A trigger valve for an unloader, comprising a pressure-operated member having free atmospheric pressure on one side thereof, a spring adapted normally to lift said member, oppositely facing valves, one of them closed when the member is lifted and the other when it is lowered, a connection from a point between the valves to the unloader, fluid pressure connection for the first valve and a connection below the pressureoperated member, the atmospheric pressure on one side of the member and the spring and connection on' the other side being adapted to maintain the first valve closed in normal position of the parts but to operate the pressure-operated member and close the second valve when the pressure in the connection falls to a predetermined value.

15. In an unloader trigger valve, a trigger valve body having openings for connection with the receiver pressure and with the unloader, a double valve controlling the passage of receiver pressure to the unloader and open to the atmosphere at an intermediate point, a pressure-operated member adapted normally to hold the valve closed and a hand operated device engaging and moving the member.

16. In an unloader trigger valve, a trigger valve body having openings for connection with the receiver pressure, with the unloader, 1 0

with the atmosphere and With a source of variant pressure adapted to approach or fall below atmospheric pressure, valves on opposite sides of the unloader connection, adapted normally to close the pressure connection and open the unloader connection to the atmosphere and in unloading position to connect the pressurewith the unloader and close the atmospheric pressure connection, a pressure-operated member controlling the operation of the said valve, open to the atmosphere on one side of the member and to the variant pressure connection on the opposite side thereof and hand operated means for moving the diaphragm GEORGE MI RICHARDS. 

